This is pretty cool; an underwater drone for $500. Want to check your anchor set? How about finding your way through a tight, poorly marked channel? Dropped a winch handle over and want to locate it? Not sure about the chain on that mooring your just picked up?

http://fathomdrone.com/ or on kickstarter https://www.kickstarter.com/projects/1359605477/fathom-one-the-affordable-modular-hd-underwater-dr(nl)